问题
计算题
计算:
(1)7a-x2-5a+2x2;
(2)(2xy+1)-(xy-1);
(3)2(x2-3x+1)-3(2x2-x-2)。
答案
解:(1)原式=7a-5a-x2+2x2
=2a+x2;
(2)原式=2xy+1-xy+1
=xy+2;
(3)原式=2x2-6x+2-6x2+3x+6
=2x2-6x2-6x+3x+2+6
=-4x2-3x+8。
计算:
(1)7a-x2-5a+2x2;
(2)(2xy+1)-(xy-1);
(3)2(x2-3x+1)-3(2x2-x-2)。
解:(1)原式=7a-5a-x2+2x2
=2a+x2;
(2)原式=2xy+1-xy+1
=xy+2;
(3)原式=2x2-6x+2-6x2+3x+6
=2x2-6x2-6x+3x+2+6
=-4x2-3x+8。
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